The present invention relates to a control method of an internal combustion engine so controlled in responsive to open-close timing and lift amount of air intake and exhaust valves of the engine, specifically to a control method of an internal combustion engine for supporting braking force by means of engine brake.
Conventionally, braking force generated by braking apparatus and supplementary braking force supported by engine brake are used in order to reduce the speed of the motor vehicle. The theory of engine brake is that, as the brake pedal is operated by foot, then the accelerator pedal is released and the throttle valve for controlling the air-intake to the engine is closed, and finally a pumping loss generated due to the negative pressure in the combustion chamber. However, non-throttle engines without throttle valves are invented as a system for reducing engine loss in order to increase fuel consumption efficiency.
In non-throttle engines, there occurs such a problem that the braking force generated by engine brake is not strong enough because the gas in the combustion chamber is not negative pressure and with low pumping loss.
An object of the present invention is to provide a control method of an internal combustion engine with which braking force while reducing the speed of the motor vehicle can be established by generating pumping loss effectively by using a variable valve mechanism enabling to control arbitrarily the open-close timing and the lift amount of air intake and exhaust valves of the engine.
In order to achieve the above object, what is provided is a control method of an internal combustion engine to be loaded on a motor vehicle having a valve mechanism including an air intake valve and an exhaust valve assembled with the cylinders of the internal combustion engine, a valve mechanism control means for controlling the valve mechanism, operation status detection means for detecting the operation status of the internal combustion engine, a step-on force detection means for detecting step-on force and an anti-lock braking system for preventing a side skid of the motor vehicle while quick braking operation, in which, when the step-on force detection means detects the step-on force and then, the operation of the anti-lock braking system is detected, either of the air-intake valve or the exhaust valve is made to be closed, and the other open one of the air-intake valve or the exhaust valve is made to be open once a single engine rotation while the piston moves from the top dead center to the bottom dead center, and the lift amounts of the valves are controlled so as to be a designated value.